Carpets, draperies, blinds, upholstery and the like are often cleaned using steam/hot water systems. Since these units usually operate on similar principles, but at different pressures and with different solvents, they are all generically and interchangeably referred to herein as carpet cleaners, carpet cleaning machines, systems, equipment, units and so on. In general, steam/hot water systems include the same basic components, namely a wand for dispensing and recovering a cleaning fluid, an optional reservoir for holding reserve fluid, a fluid pump for providing pressurized cleaning fluid at the wand, an air pump (sometimes referred to as a vacuum pump) for sucking up spent fluid, and a spent fluid holding tank. Carpet cleaning equipment contemplated herein ranges from relatively small residential units to large, truck mounted units with long hoses reaching from the truck to the surface to be cleaned.
The efficacy of steam/hot water type carpet cleaning equipment is dependent upon many factors, including operator skill and experience, the quality and condition of the machine, the solvents used, the temperature and pressure at which the cleaning fluid is dispensed, and the vacuum with which the cleaning fluid is recovered. Due to the many factors involved, it is not unusual to experience some or all of the following problems. First, an operator may keep his equipment in a poor state of maintenance. For example, the holding tanks may not be emptied regularly, or the equipment may not be serviced regularly. Second, operators tend to push their equipment to the limit, for example by setting the thermostat on the heater at an unsafe level. Third, operators do not necessarily know how to operate the equipment properly. This problem can be addressed to some extent with operator manuals, but such manuals are of little use where the manuals are not available at an operating site, or an operator is unwilling to wade through a manual to find the relevant section. Fourth, operators do not necessarily keep accurate records of operating conditions, so that when an equipment failure occurs it is often almost impossible to pinpoint the cause as being something which is or is not covered by warranty. Fifth, when equipment failures do occur, the equipment may be at a great distance from a suitable repair facility, and individual operators may not have the skills to effectively diagnose the failure.
Even where carpet cleaning equipment is maintained in top shape and is operated properly, a particular machine may not have the capacity required for a particular job. Commonly the heater is inadequate to provide sufficiently hot solvent, or the vacuum pump does not draw a sufficient volume of air to adequately remove spent solvent. Of course, it is not difficult to design ever larger carpet cleaning machines having larger heater and air pumps, but this generally makes the equipment ever larger and noisier. Many truck mounted units are already so loud that their use in residential and even commercial districts is unacceptable.
Thus, there exists a need to improve the operation of carpet cleaning equipment in a manner which can resolve the above mentioned problems, and there is nothing in the art which teaches or suggests how that can be accomplished. UK patent application GB 2,243,992 (the '992 application), for example, discloses a carpet cleaning machine which incorporates a microprocessor, but that microprocessor is not used to improve the operation of the equipment. Instead, the '992 application only uses the microprocessor as a safety switching mechanism, to distance the operator from the high voltage switches connected to the various pumps. Other patents such as U.S. Pat. No. 5,075,921 are directed to a particular component of a carpet cleaning system, but do not address the problems set forth above.